|Publication number||US5109416 A|
|Application number||US 07/590,087|
|Publication date||Apr 28, 1992|
|Filing date||Sep 28, 1990|
|Priority date||Sep 28, 1990|
|Publication number||07590087, 590087, US 5109416 A, US 5109416A, US-A-5109416, US5109416 A, US5109416A|
|Inventors||James J. Croft|
|Original Assignee||Croft James J|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (72), Classifications (10), Legal Events (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to speakers to produce sound in a response to an audio signal, and, in particular, relates to such speakers for the production of an ambience or "surround sound" signal.
2. Background Art
Ideally, sound reproduced through a sound reproduction system, such as that of a stereo high fidelity system, a television, or the like, would sound like the original source. In part, this means that the reproduced sound should have a spatial dimension or quality in that a listener should perceive the sound as being distributed in space as it would be if listening to the original performance. Unfortunately, a problem with conventional sound reproduction systems is the tendency of the sound to be localized by the listener at the loudspeakers, or imaged at a point relative to the loudspeakers.
When a listener hears an original performance, the listener receives some acoustical signals which permit the listener to localize the source of the sound, for example, a particular singer or instrument, and other signals which provide a sense of a spatial dimension, which will be referred to from time-to-time hereinafter as "ambience". The first category of signal is comprised of those which travel along a substantially straight path from the source to the listener; the second set of signals, which are not readily localizable, are those which are reflected off of the walls, ceiling, floor, fixtures, and the like of the listening area. It is these latter singals which provide the sense of ambience or spatiality, and this quality is imparted both by their arrival at the listener from a variety of directions, and by the fact that their arrival is delayed relative to those signals which travel directly from the source to the listener; this delay is the result of the longer paths which the reflected signals must travel. The ambience signals may consequently be delayed on the order of 10 or more milliseconds as compared to the direct path signals.
A number of approaches have been proposed for reproducing the ambience signals with a sound reproduction system. Some of these have employed electronic delay circuitry to delay the signal from the left and right channels of the amplifier of a conventional stereo system, the delayed output then being supplied to dedicated right and left speakers which project the delayed signal along direct paths to the listener. While this approach has achieved some success in producing a "surround sound" effect, it possesses a number of inherent disadvantages: not only is the delay circuitry (which typically requires housing in a separate component) both relatively expensive and noisy, but the approach also ordinarily employs two dedicated "surround sound" speakers, in addition to the conventional, non-delayed speakers of the stereo system.
Another approach is disclosed in U.S Pat. No. 4,596,034, which shows a system in which each channel of a stereo system is reproduced in full by first and second transducers with the output of the first transducer being 180 degrees out of phase with repect to the output of the second transducer. The transducers are positioned such that their acoustic outputs, that is, their sound pressure lobes, are directed to either side of the listener, and a pressure minimum, or null zone, formed between the two lobes is directed towards the listener, eliminating all direct path sound so as to provide a sound field which prevents the listener from localizing the speakers. While this arrangement may help produce an enhanced sense of sound distribution and a decreased awareness that the sound is coming from speakers, this system also possesses several inherent disadvantages. The most significant of these lies in the very fact the the system is intended to prevent the listener from localizing sound for the whole of both channels of the stereo system; in other words, this arrangement renders it difficult or impossible for the listener to localize any of the acoustical signals which are reproduced by the system, regardless of whether those signals were originally recorded as direct path signals or indirect path signals. This is undesirable in that it consequently makes it impossible for the listener to localize those sources (e.g., a singer or particular instrument) where a degree of localization is desirable. The practical result is that the reproduced sound is preceived as being formless or "mushy".
Accordingly, there exists the need for a sound reproduction system which reproduces a non-localizable ambience signal, yet which also reproduces localizable direct-path acoustic signals for those sounds for which such localizability is desirable. Furthermore, there is a need for such a system which does not require noisy and expensive signal delay circuitry, and for such a system which does not require two dedicated speakers to reproduce the ambience acoustical signal.
The present invention has solved the problems cited above, and comprises generally a dipole speaker for use with a sound reproduction system so as to produce an acoustical ambience signal in a defined listening area, the reproduction system having at least first and second audio signal channels and at least one other speaker which generates an acoustical signal on a substantially direct path to the listener. The dipole speaker comprises at least one transducer for generating an acoustic output in response to an audio signal input, the transducer being configured so that the output signal is characterized by first and second sound pressure lobs which are directed along a first and second axes which extend from the transducer, the first and second sound pressure lobes being 180 degrees out of phase so that they cancel one another out to form a null zone which extends outwardly from the transducer along a third axis. The transducer is connected to the sound reproduction system so that it receives an input signal which is the difference signal between the first and second channels of the system, the transducer generating an acoustic output in response to this difference signal. The transducer is mounted so that the dipole speaker is positionable to place the listener in alignment with the null zone which extends from the transducer along the third axis, and so that the first and second sound pressure lobes which extend outwardly along the first and second axes are reflected from walls of the listening area so as to arrive at the listener by way of indirect paths which are substantially longer than the direct path from the other speaker which is connected to the sound reproduction system, the longer indirect paths causing the arrival of the output from the dipole speaker to be delayed relative to the arrival of the output from the direct path speaker.
The transducer of the dipole speaker may comprise a unitary speaker having a diaphragm which is deflected in first and second directions perpendicular to a transverse plane of said diaphragm in response to the signal input, the first and second directions being substantially opposite to one another, and the third axis (along which the null zone extends from the speaker) being substantially coplanar with the transverse plane of the diaphragm. The unitary speaker may be mounted in a planar baffle which is substantially coplanar with the transverse plane of the diaphragm, the dipole speaker being positionable in the listening area with the baffle aligned so that the listener's position is within the plane of the baffle.
The transducer may also comprise first and second speakers which are configured to generate the first and second sound pressure lobes in response to the audio signal input. The first and second speakers are connected to the sound reproduction system so that the first and second sound pressure lobes generated are 180 degrees out of phase. The first and second speakers may be mounted in a unitary, planar baffle so that the first and second sound pressure lobes are radiated outwardly along the first and second axes perpendicularly from the baffle, or the first and second speakers may be mounted in first and second substantially planar baffles which are mounted parallel to one another in a speaker cabinet. The speaker cabinet may be substantially enclosed so as to form a confined air space intermediate the inner surfaces of the first and second baffles, so that as the first and second speakers generate the first and second sound lobes which are 180 degrees out of phase, the diaphragm of one speaker moves inwardly toward the speaker box so as to force a volume of air into the combined air space and the diaphragm of the other speaker moves outwardly from the speaker box so as to withdraw a volume of air from the speaker box which is substantially equal to that which has been forced into the box, so that the inward and outward movement of the diaphragm of each speaker is assisted by the complementary inward and outward movement of the diaphragm of the other speaker.
A transducer of the dipole speaker may have first and second leads such that the transducer generates an acoustic output in response to an audio signal input applied across the leads, the first lead being connected to a selected output of the first channel of the stereo reproduction system, each channel of the system including an output having a positive polarity and an output having a negative polarity, and the negative lead of the transducer being connected to a selected output of the second channel of the system, the selected output of the second channel having the same polarity as the selected output of the first channel, so that the signal input applied across the leads of the transducer is a difference signal between output of the two channels.
FIG. 1 is an overhead view of a section taken through a dipole speaker embodying the present invention, this embodiment being provided with a single transducer which produces a null zone which is aligned towards the listener;
FIG. 2 is an overhead schematic view of the dipole speaker of FIG 1, showing the first and second sound pressure lobes and null zones which are produced by the speaker in response to an audio input signal;
FIG. 3 is an overhead schematic view of the dipole speaker of FIGS. 1-2, with the speaker being connected to an illustrative sound reproduction system (a television) and positioned in a defined listneing area so that the acoustic signals are directed against the walls of the listening area and reflected to listener, the dipole speaker being shown in a first position in front of the listener, and in a second, alternative position behind the listener;
FIG. 4 is an overhead view of a section through another dipole speaker embodying the present invention, this embodiment having first and second transducers mounted in a single baffle so as to project sound lobes in opposite directions therefrom;
FIG. 5 is an overhead view of a section through another dipole speaker embodying the present invention, this embodiment having two transducers mounted in parallel baffles in a speaker enclosure.
FIG. 6 shows one exemplary arrangement for connecting the dipole speaker 10 to a stereo amplifier 130 so that the speaker 10 receives a difference signal.
FIG. 1 shows an overhead view of a dipole speaker 10 which comprises generally a loudspeaker assembly 12 and a cabinet assembly 14. Loudspeaker assembly 12 is preferably a conventional full range transducer having a frequency range, for example, of 100 Hz through 7 KHz. Loudspeaker assembly 12 has a diaphragm portion 16, which, in this example, is a substantially conical diaphragm having a mounting ring 18 at its wide, projection or mouth end, and a driver portion 20 at its narrow end. Driver portion 20 is provided in a conventional manner with a positive and negative connections or leads 22 and 24, so that loudspeaker 12 generates an acoustic signal in response to an audio signal input applied across leads 22 and 24. As will be discussed below, these acoustic signals are projected in first and second sound pressure lobes which extend in opposite direction from loudspeaker assembly 12, and which are 180 degrees out of phase so as to form a null zone which, in the example of FIG. 1, extends in a transverse plane which is substantially perpendicular to the longitudinal axis 26 of diaphragm portion 16.
Cabinet assembly 14, in turn, comprises generally a baffle plate 30, a support bracket 32, and an acoustically transparent enclosure 34, the latter being constructed of any suitable material such as speaker cloth, acoustic foam or the like. Baffle plate 30, which is preferably constructed of particle board or the like, is provided with a circular opening or bore 36 through which conical diaphragm 16 passes, mounting ring 18 being mounted to a first side of baffle plate 30 so that the conical diaphragm portion 16 extends through bore 36 outwardly from the other side of baffle plate 30. Accordingly, the sound pressure lobes generated by diaphragm portion 16 extend outwardly to the right and left from baffle plate 30, along axis 26 shown in FIG. 1, and baffle plate 30 is mounted to diaphragm portion 16 so that it extends in a transverse plane thereof. Accordingly, baffle plate 30 lies in the plane of the null zone formed between the first and second sound pressure lobes. The edge of baffle plate 30 is mounted at right angles to support bracket 32, the resulting T-shaped arrangement facilitating convenient placement of dipole speaker 10 against a wall 34 so that baffle plate 30, and the null zone produced by loudspeaker assembly 12, project therefrom towards the location of the listener.
FIG. 2 shows the distribution pattern of sound pressure lobes and null zones formed by the operation of dipole speaker 10. As will be described in greater detail below, dipole speaker 10 is connected to a stereo amplifier, or other suitable stereo audio signal source, so that it receives a difference signal from between the left and right channels of the source. As is shown in FIG. 6, this may be accomplished by connecting leads 22 and 24 across the positive outputs of both left and right channels. In the difference signal, the "mono" signals which are generated on the two channels (i.e. signals which are substantially the same on both the left and right channels) are cancelled out, and thus these do not produce any acoustic signal at the dipole speaker. If, however, there is a difference between the signals in the two channels, the resulting difference signal at the dipole speaker causes it to generate an acoustic output. In ordinary stereo reproduction, the signals of the right and left hand channels may be considered as containing both "mono" signals and "difference" signals. The advantage of using only the difference signals to power the dipole speaker 10 is that it is the difference signals which tend to provide the listener with a perceived ambience sound. Essentially, this is because the stereo microphones are normally focused on the point sources (e.g., a singer) when stereo recording is made, these point sources being reproduced more or less as mono-type signals (which are cancelled out at the dipole speaker 10). However, those sounds in the original performance which are not centrally located, and hence not focused on by the stereo microphones (e.g., those sounds which approach the microphones from off to the right or left of the central singer or instrument), tend to be recorded differently by the two microphones; when these are reproduced, the difference between the right and left channels produces the difference signal which drives the dipole speaker 10. Since these sounds represent those which are not the central focus of the stereo recording, but rather those which approach the recording area from the surrounding area (i.e., those sounds which have been reflected back from walls, ceilings, and the like), these are the sounds that are perceived by the listener during the original performance as ambience sounds (as opposed to direct path sounds), and, when reproduced by means of the dipole speaker of the present invention, they are again perceived by the listener as ambience sounds.
It should be noted at this point that although, for illustrative purposes, this description focuses on the use of a dipole speaker in conjunction with a stereo sound reproduction system which has two channels, the present invention may be applied to any sound reproduction system which has a plurality of channels, including those systems having more than two channels.
FIG. 2 shows the first and second sound pressure lobes 40 and 42 which are produced by dipole speaker 10 in response to the difference signal between the first and second channels of the stereo reproduction system, and which are projected outwardly in the opposite directions indicated by arrows 44 and 46. Inasmuch as the dipole speaker is being driven with the difference signal, by definition the first side of loudspeaker assembly 12 emits a left-minus-right signal (in this case represented by sound pressure lobe 42), while the other side emits a right-minus left signal (as represented by sound pressure lobe 40). Since these lobes 40 and 42 are 180 degrees out of phase, they cancel one another out where they meet to produce a null zone which is substantially co-planar with the plane of baffle plate 30, and which extends outwardly from dipole speaker 10 generally in the directions indicated by arrows 50.
It will be understood that the single dipole speaker 10 thus produces, in separate sound pressure lobes, both a left-minus-right and a right-minus-left signal. This maintains the separation of the rear channel, and permits the single dipole speaker 10 to, in essence, simulate two separate loudspeakers, as are used in conventional "surround-sound" systems to individually generate the left-minus-right and right-minus-left signals.
FIG. 3 shows dipole speaker 10 placed in a defined listening area provided by room 52, with the projection paths of the sound pressure lobes and null zone oriented so that the sound reproduced by the dipole speaker is perceived by listener 54 as ambience sound. Two approaches are shown for arranging dipole speaker 10 relative to the listener 54, in the first case the dipole speaker being positioned in front of the listener, and in the second case the dipole speaker being positioned behind the listener. In both cases, the listener 54 is positioned within room 52, which has front and rear walls 56 and 58, and left and right side walls 60 and 62.
In the first arrangement, the dipole speaker 10 is positioned in front of listener 54 and adjacent to front wall 56; in the example illustrated, dipole speaker 10 is positioned in back of a conventional stereo-equipped television set 64 which is viewed by listener 54, and which is provided with stereo sound reproduction system having left and right channels. As was discussed above, dipole speaker 10 is connected to the stereo reproduction system so as to receive a difference signal from between the two channels. Dipole speaker 10 is oriented so that the plane of its baffle plate 30 is generally aligned with the position of listener 54, this being conveniently accomplished here by mounting dipole speaker 10 to the back of the television cabinet 66 so that the plane of baffle plate 30 is perpendicular to that of the viewing screen 68. The null zone consequently extends from dipole speaker 10 in the direction indicated by arrows 50 so as to include the listener's position, thereby preventing any sound from reaching listener 54 along a direct path from dipole speaker 10 and avoiding undesirable localization of the sound produced by the dipole speaker. The R-L and L-R sound lobes are, in turn, projected outwardly from dipole speaker 10 along the paths indicated by arrows 44 and 46 against side walls 62 and 60, from which the sound pressure lobes are reflected and reach the listener more or less along the indirect paths indicated by arrows 44' and 46'. Thus, since the direct path sound has been cancelled out, the first audible signal arriving at the listener's ears from speaker 10 is the wall reflection, and therefore the sound sources are sensed as coming from the sides (or possibly the rear) of room 52. Since the distance traveled by these reflected sounds (along paths indicated by arrows 44--44' and 46--46') are considerably longer than the distance which the sound would have traveled by way of a direct path to the listener, their arrival at the listener is delayed relative to the time at which a corresponding direct path signal would arrive. In this case, the arrival of the ambience sound signals is delayed relative to the direct-path acoustic signals which are generated by the conventional left and right frontally-directed speakers 70 and 72 of television set 64, which travel to the listener 54 along the direct paths indicated by arrows 74 and 76. Hence, not only is the ambient sound projected by dipole speaker 10 non-localizable, but its arrival at the listener is delayed relative to that of the direct path signals, both of which enhance the ambience sound or "surround sound" effect. Furthermore, it will be observed that the delay of the ambience signal is achieved with out the need for expensive and noisy delay circuitry.
The system of the present invention avoids the problems of unclear, "mushy"-sounding signals (as were previously discussed with reference to the system of the Moncrieff patent) by projecting those signals which are desirably localizable along the direct paths 74 and 76 from forward facing stereo speakers 70 and 72, on which are reproduced the whole of the left and right channels of the stereo system, thus permitting the listener to image the location of the signals which are the focus of the recording.
Since the ambience signal generated by dipole speaker 10 is intended to be non-localizable, it is not necessary that speaker 10 be positioned in front of the listener, and it can thus be positioned elsewhere in the room so long as the proper orientation with respect to the listener is maintained. In the second arrangement shown in FIG. 3, the dipole speaker 10' is positioned behind the listener 54 (who remains oriented so as to watch television 64 and listen to its direct path stereo speakers 70 and 72), against the rear wall 58 of room 52. Speaker 10' remains oriented, however, with its planar baffle plate 30' aligned toward listener 54 so that the null zone extends in the direction indicated by arrow 50' to include the listener's location. The sound lobes are consequently projected in the directions indicated by arrows 78 and 80 against side walls 62 and 60, from which they are reflected along the indirect paths indicated by arrows 78' and 80' to listener 54. If desired, a plurality of dipole speakers 10 can be so utilized, preferably arranged in a symmetrical array about the listener, with each having its baffle plate and null zone aligned toward the listener and so that its sound pressure lobes are reflected off of the walls of the room.
In the above described arrangements, the desired delay of the ambience signals relative to the direct path signals is produced by means of the extended path of travel which results from reflecting the sound lobes off of the walls of the room to the listener; this technique has proven eminently suitable for use in rooms having dimensions of roughly 12 feet by 20 feet or greater, this providing sufficient distance to the walls in order to achieve the desired delay of some ten to twenty milliseconds. For use in smaller rooms, or for enhanced ambience effects (e.g. to simulate a larger environment, such as that of a concert hall), it may be desirable to include some delay circuitry to delay the input signal going to the dipole speaker relative to that going to the direct path speakers so as to ensure the desired time delay, although by use of the reflected paths, the dipole speaker of the present invention enables the amount of such delay circuitry to be kept to a minimum. In such an arrangement, the left-minus-right input described above could, as is current practice in Dolby™ "surround-sound" processors, be routed through a delay circuit and then through a Dolby™ noise reduction circuit and a low pass filter (which, for reasons discussed below, reduces the high frequency output), and then the subsequent output could be supplied via an amplifier to the single dipole speaker of the present invention rather than the dual-speaker arrangement of the currect-practice systems. The present invention may similarly be applied to a wide variety of other difference signal-derived ambience or "surround-sound" multichannel processors, including, for example, the THX™ systems processors which are known to those skilled in the art.
While the dipole speaker 10 having a single internal loudspeaker assembly 12 is a notably inexpensive and effective arrangement, it will be noted that, due to the construction of the single loudspeaker assembly, the signal projected from its first side will almost inevitably be slightly different than that projected from its other side. Because the two signals may thus differ slightly, a less than perfect null zone may be formed between the two. Although a suitable loudspeaker assembly might be provided to generate a more symmetrical wave form on both sides, this would likely have to be more or less unique to this application, instead of being an inexpensive "off-the-shelf" loudspeaker. Accordingly, it may prove advantageous in terms of economy and sound quality to provide a pair of identical speakers in place of the single speaker described above, with the pair of speakers being connected to the signal source so as to be 180 degrees out of phase. FIG. 4 shows such an arrangement, in which identical first and second loudspeaker assemblies 80 and 82 are mounted in a single planar baffle plate 84. Baffle plate 84 is provided with first and second circular openings 86 and 88 in which the mouth ends of loudspeaker assemblies 80 and 82 are mounted so as to project their respective acoustic signals in opposite directions, each loudspeaker assembly 80, 82 having a conical diaphragm 90, 92 which extends back through the opening 86, 88 to a driver portion 94, 96. Baffle plate 84 is, in turn, mounted at each end to a support bracket 98, which forms an integral part of a speaker cabinet 100. Since the identical loudspeaker assemblies 80 and 82 produce identical acoustic signals which are 180 degrees out-of-phase, a near-perfect null zone is formed along the plane of baffle plate 84.
FIG. 5 shows another dual-transducer arrangement, and in this case the identical first and second loudspeaker assemblies 110 and 112 are mounted in separate, parallel planar baffle plates 114 and 116. The two baffle plates are connected by end walls 118 and 119, which, together with top and bottom walls (not shown), may preferably form an enclosed air space within speaker cabinet enclosure or assembly 120. This arrangement is particularly advantageous in that not only is a near-perfect null zone formed in the plane between the loudspeakers, but also the 180 degree out-of-phase movement of the diaphragms 122, 124 of loudspeaker assemblies 110 and 112 (which are connected to the difference signal 180 degrees out of phase with each other) move in a complimentary fashion so as to eliminate any air spring in the enclosed speaker cabinet assembly 120, each movement of a loudspeaker assembly being assisted by the complementary movement of the other loudspeaker assembly. In other words, as the diaphragm of the first loudspeaker moves inwardly toward the enclosed speaker cabinet or box so as to force a volume of air into the confined air space, the diaphragm of the other loudspeaker assembly moves outwardly from the cabinet so as to withdraw an equal volume of air, the inward and outward movement of each loudspeaker assembly thus assisting the inward and outward movement of the other loudspeaker assembly. This arrangement consequently allows for the use of high efficiency speakers having lightweight cones and relative low mass magnets in their driver portions.
Each of the loudspeaker assemblies used in the dual-transducer dipole speakers 78 and 108 may preferably be a conventional five inch speaker having a range of response from about 100 Hz to 7 KHz. For the single loudspeaker assembly version shown in FIG. 1, a single 8 inch speaker having a similar frequency range has been found suitable. As was noted above, a low pass filter may be used to eliminate high frequencies, preferably be in the 2,000 Hz and above range, good results having been achieved with the system of the present invention using a range of 300 Hz to 2,000 Hz. Use of the lower frequency range is particularly advantageous with the single-transducer arrangement of FIG. 1, inasmuch as this renders it significantly easier to attain near-symmetrical wave forms on either side of the speaker diaphragm. Furthermore, the lower frequency range signals taken from the difference signal are most suitable for realistically reproducing the ambience sound, inasmuch as in the original performance the higher frequency sounds are typically absorbed by walls, furniture, wall hangings and the like, and the remaining reflected sounds (which are perceived as ambience) are consequently more in the lower frequency range. As an additional refinement, it is desirable that the dipole speaker generate sound at a level which is somewhat louder (e.g., 3 dB louder) than that produced by the two, conventional front facing speakers. Thus, after the sound produced by the dipole speaker is reflected off the walls of the listening area, it will be reduced in intensity and perceived by the listener as being softer, and thus more like true ambience sound.
FIG. 6 shows one exemplary arrangement for connecting the dipole speaker 10 to a stereo sound reproduction amplifier 130 so that the dipole speaker receives a difference signal. Stereo amplifier 130, in conventional manner, is provided with left and right channels, indicated generally by reference numerals 132 and 133. The output for left channel 132 is provided by a positive output jack 138 and a negative output jack 140; similarly, the output for the right channel is provided by a positive output jack 142 and a negative output jack 144. In conventional fashion, the left, front facing, direct path stereo speaker 150 has a first lead 152 which is connected to the positive output jack 138 of left channel 132, and a second lead 154 which is connected to the negative output jack 140. Similarly, right forward facing speaker 160 has a first lead 162 which is connected to the positive output jack 142 of the right channel 133, and a second lead 164 which is connected to the negative output jack 144. Left and right speakers 150 and 160 each have conventional, forward facing diaphragm portions 166 which are mounted in baffle plates 168, and which are driven by driver portions 170 so as to produce conventional stereo acoustical signals which travel on the direct paths 74 and 76 shown in FIG. 3 to the listener 54.
Dipole speaker 10, as was described above, is provided with first and second leads 22 and 24. Lead 22 is connected to the positive output jack 138 of left channel 132, and the other lead 24 is connected to the positive output jack 142 of the right channel 133. As was described above, this inexpensive and effective arrangement provides dipole speaker 10 with an audio input signal which represents the difference between the signals of the left and right channels outputted by amplifier 130.
It is to be understood that various modifications could be made to the illustrative embodiments shown herein without departing from the spirit and scope of the present invention. Accordingly, the invention is not to be limited except as by the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3588355 *||Jul 26, 1968||Jun 28, 1971||Holm James P||Stereophonic loudspeaker system|
|US4596034 *||Mar 22, 1982||Jun 17, 1986||Moncrieff J Peter||Sound reproduction system and method|
|US4759066 *||May 27, 1987||Jul 19, 1988||Polk Investment Corporation||Sound system with isolation of dimensional sub-speakers|
|US4819269 *||Jul 21, 1987||Apr 4, 1989||Hughes Aircraft Company||Extended imaging split mode loudspeaker system|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5333200 *||Aug 3, 1992||Jul 26, 1994||Cooper Duane H||Head diffraction compensated stereo system with loud speaker array|
|US5553147 *||May 11, 1993||Sep 3, 1996||One Inc.||Stereophonic reproduction method and apparatus|
|US5742691 *||Feb 21, 1997||Apr 21, 1998||Ambourn; Paul R.||Surround sound converter|
|US5889875 *||Jul 1, 1994||Mar 30, 1999||Bose Corporation||Electroacoustical transducing|
|US6219426 *||Mar 21, 1997||Apr 17, 2001||Drew Daniels||Center point stereo field expander for amplified musical instruments|
|US6363157 *||Aug 28, 1997||Mar 26, 2002||Bose Corporation||Multiple element electroacoustic transducing|
|US6870941 *||Jul 15, 2002||Mar 22, 2005||Glenn A. Marnie||Dipole radiating dynamic speaker|
|US7130430||Dec 18, 2001||Oct 31, 2006||Milsap Jeffrey P||Phased array sound system|
|US7525440||Jun 1, 2005||Apr 28, 2009||Bose Corporation||Person monitoring|
|US7529376 *||Sep 24, 2004||May 5, 2009||Yamaha Corporation||Directional speaker control system|
|US7577260 *||Sep 29, 2000||Aug 18, 2009||Cambridge Mechatronics Limited||Method and apparatus to direct sound|
|US7580530||Sep 24, 2004||Aug 25, 2009||Yamaha Corporation||Audio characteristic correction system|
|US7729498||Jan 9, 2007||Jun 1, 2010||American Technology Corporation||Modulator processing for a parametric speaker system|
|US8031879||Dec 12, 2005||Oct 4, 2011||Harman International Industries, Incorporated||Sound processing system using spatial imaging techniques|
|US8041061 *||Oct 4, 2004||Oct 18, 2011||Altec Lansing, Llc||Dipole and monopole surround sound speaker system|
|US8121336 *||Apr 5, 2007||Feb 21, 2012||Harman International Industries, Incorporated||Directional loudspeaker to reduce direct sound|
|US8199931||Jun 12, 2012||American Technology Corporation||Parametric loudspeaker with improved phase characteristics|
|US8275137||Sep 25, 2012||Parametric Sound Corporation||Audio distortion correction for a parametric reproduction system|
|US8315403 *||Jul 6, 2005||Nov 20, 2012||Yamaha Corporation||Method for controlling directivity of loudspeaker apparatus and audio reproduction apparatus|
|US8345883||Jan 1, 2013||Yamaha Corporation||Audio playback method and apparatus using line array speaker unit|
|US8369533||Jan 21, 2009||Feb 5, 2013||Yamaha Corporation||Array speaker apparatus|
|US8391516 *||Aug 14, 2008||Mar 5, 2013||Airsound Llp||Method of using an audio device for improving sound reproduction and listening enjoyment|
|US8457324 *||Jun 4, 2013||Honeywell International Inc.||Directional speaker system|
|US8594350||Jan 19, 2004||Nov 26, 2013||Yamaha Corporation||Set-up method for array-type sound system|
|US8767984||Dec 8, 2008||Jul 1, 2014||Airsound Llp||Apparatus and method for reproduction of stereo sound|
|US8995697 *||Jun 16, 2011||Mar 31, 2015||Definitive Technology, Llc||Bipolar speaker with improved clarity|
|US9185490 *||Nov 14, 2011||Nov 10, 2015||Bradley M. Starobin||Single enclosure surround sound loudspeaker system and method|
|US9374641||Jun 25, 2013||Jun 21, 2016||Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.||Device and method for driving a sound system and sound system|
|US20030118198 *||Nov 12, 2002||Jun 26, 2003||American Technology Corporation||Biaxial parametric speaker|
|US20030185404 *||Dec 18, 2001||Oct 2, 2003||Milsap Jeffrey P.||Phased array sound system|
|US20040008857 *||Jul 15, 2002||Jan 15, 2004||Marnie Glenn Arthur||Dipole radiating dynamic speaker|
|US20040013271 *||Aug 14, 2001||Jan 22, 2004||Surya Moorthy||Method and system for recording and reproduction of binaural sound|
|US20060072773 *||Oct 4, 2004||Apr 6, 2006||Altec Lansing Technologies, Inc.||Dipole and monopole surround sound speaker system|
|US20060088175 *||Dec 12, 2005||Apr 27, 2006||Harman International Industries, Incorporated||Sound processing system using spatial imaging techniques|
|US20060126878 *||Feb 6, 2006||Jun 15, 2006||Yamaha Corporation||Audio playback method and apparatus using line array speaker unit|
|US20060153391 *||Jan 19, 2004||Jul 13, 2006||Anthony Hooley||Set-up method for array-type sound system|
|US20060204022 *||Feb 24, 2004||Sep 14, 2006||Anthony Hooley||Sound beam loudspeaker system|
|US20060273914 *||Jun 1, 2005||Dec 7, 2006||Carreras Ricardo F||Person monitoring|
|US20070019816 *||Sep 24, 2004||Jan 25, 2007||Yamaha Corporation||Directional loudspeaker control system|
|US20070036366 *||Sep 24, 2004||Feb 15, 2007||Yamaha Corporation||Audio characteristic correction system|
|US20070041590 *||Aug 16, 2005||Feb 22, 2007||Tice Lee D||Directional speaker system|
|US20070110268 *||Nov 19, 2004||May 17, 2007||Yusuke Konagai||Array speaker apparatus|
|US20070223763 *||Sep 16, 2004||Sep 27, 2007||1... Limited||Digital Loudspeaker|
|US20070230724 *||Jul 6, 2005||Oct 4, 2007||Yamaha Corporation||Method for Controlling Directivity of Loudspeaker Apparatus and Audio Reproduction Apparatus|
|US20070269062 *||May 14, 2007||Nov 22, 2007||Rene Rodigast||Device and method for driving a sound system and sound system|
|US20070269071 *||Aug 10, 2005||Nov 22, 2007||1...Limited||Non-Planar Transducer Arrays|
|US20080063214 *||Jan 9, 2007||Mar 13, 2008||American Technology Corporation||Modulator processing for a parametric speaker system|
|US20080247575 *||Apr 5, 2007||Oct 9, 2008||Harman International Industries, Incorporated||Directional loudspeaker to reduce direct sound|
|US20090067635 *||Aug 21, 2008||Mar 12, 2009||Airsound Llp||Apparatus and method for reproduction of stereo sound|
|US20090129602 *||Jan 21, 2009||May 21, 2009||Yamaha Corporation||Array speaker apparatus|
|US20090161880 *||Feb 24, 2009||Jun 25, 2009||Cambridge Mechatronics Limited||Method and apparatus to create a sound field|
|US20090296964 *||Jul 11, 2006||Dec 3, 2009||1...Limited||Compact surround-sound effects system|
|US20100061574 *||Apr 28, 2006||Mar 11, 2010||Gp Acoustics (Uk) Limited||Audio system and sound field controller|
|US20100239108 *||Aug 14, 2008||Sep 23, 2010||Airsound, Llp||Method of improving sound reproduction and listening enjoyment|
|US20100303264 *||Dec 8, 2008||Dec 2, 2010||Airsound Llp||Apparatus and method for reproduction of stereo sound|
|US20110158445 *||May 26, 2009||Jun 30, 2011||Sl Audio A/S||Dipole loudspeaker with acoustic waveguide|
|US20120014544 *||Jan 19, 2012||Gladwin Timothy||Bipolar speaker with improved clarity|
|US20120121092 *||May 17, 2012||Starobin Bradley M||Single enclosure surround sound loudspeaker system and method|
|CN101919267B||Dec 8, 2008||Jul 10, 2013||航音有限公司||An improved apparatus and method for reproduction of stereo sound|
|DE4244397A1 *||Dec 29, 1992||Jun 30, 1994||Waldemar Kehler||Method for reproducing acoustic wave fields|
|DE102013210709A1||Jun 7, 2013||Dec 11, 2014||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.||Schallstrahler-Anordnung für aktive Schalldämpfer|
|EP1670282A1 *||Sep 24, 2004||Jun 14, 2006||Yamaha Corporation||Directional loudspeaker control system|
|EP2129164A1 *||May 27, 2008||Dec 2, 2009||SLH Audio A/S||Dipole loudspeaker with acoustic waveguide|
|WO1994015439A2 *||Dec 29, 1993||Jul 7, 1994||Waldemar Kehler||Method of polarizing acoustic fields in particular with the aim of achieving an extremely broad, non-localized and spatial stereo effect requiring little space|
|WO1994015439A3 *||Dec 29, 1993||Aug 18, 1994||Waldemar Kehler||Method of polarizing acoustic fields in particular with the aim of achieving an extremely broad, non-localized and spatial stereo effect requiring little space|
|WO1994027416A1 *||May 6, 1994||Nov 24, 1994||One Inc.||Stereophonic reproduction method and apparatus|
|WO1998042159A1 *||Jan 24, 1998||Sep 24, 1998||Drew Daniels||Center point stereo reproduction system for musical instruments|
|WO2006041755A2 *||Oct 4, 2005||Apr 20, 2006||Altec Lansing Technologies, Inc.||Dipole and monopole surround sound speaker system|
|WO2007021861A2 *||Aug 10, 2006||Feb 22, 2007||Honeywell International, Inc.||Directional speaker system|
|WO2009071911A2 *||Dec 8, 2008||Jun 11, 2009||Airsound Llp||An improved apparatus and method for reproduction of stereo sound|
|WO2009071911A3 *||Dec 8, 2008||Aug 27, 2009||Airsound Llp||An improved apparatus and method for reproduction of stereo sound|
|WO2009143852A1||May 26, 2009||Dec 3, 2009||Slh Audio A/S||Dipole loudspeaker with acoustic waveguide|
|U.S. Classification||381/304, 381/307, 381/308, 381/1|
|International Classification||H04R5/02, H04R1/32|
|Cooperative Classification||H04R5/02, H04R1/323|
|European Classification||H04R1/32B, H04R5/02|
|Oct 23, 1995||FPAY||Fee payment|
Year of fee payment: 4
|Nov 23, 1999||REMI||Maintenance fee reminder mailed|
|Apr 7, 2000||FPAY||Fee payment|
Year of fee payment: 8
|Apr 7, 2000||SULP||Surcharge for late payment|
|Feb 20, 2001||AS||Assignment|
Owner name: CROFT, JAMES J., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CARVER CORPORATION;REEL/FRAME:011541/0208
Effective date: 20001129
|Oct 27, 2003||FPAY||Fee payment|
Year of fee payment: 12
|Dec 7, 2010||AS||Assignment|
Owner name: LRAD CORPORATION, CALIFORNIA
Free format text: CHANGE OF NAME;ASSIGNOR:AMERICAN TECHNOLOGY CORPORATION;REEL/FRAME:025466/0409
Effective date: 20100324
Owner name: PARAMETRIC SOUND CORPORATION, NEVADA
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|Oct 8, 2014||AS||Assignment|
Owner name: TURTLE BEACH CORPORATION, CALIFORNIA
Free format text: CHANGE OF NAME;ASSIGNOR:PARAMETRIC SOUND CORPORATION;REEL/FRAME:033917/0789
Effective date: 20140520